1. Field of the Invention
The invention relates to a vehicle that can be allowed to travel by power of a traveling motor by using discharge electric power of an alkaline secondary battery.
2. Description of Related Art
A voltage value of a secondary battery is monitored so that over-discharge of the secondary battery is prevented. When the voltage value of the secondary battery decreases below a voltage value (referred to as an over-discharge voltage value) corresponding to an over-discharge state, the secondary battery is determined to be in the over-discharge state. When the secondary battery is in the over-discharge state, charging and discharging of the secondary battery are not performed.
A vehicle is suddenly stopped if the secondary battery is determined to be in the over-discharge state and the charging and the discharging of the secondary battery are stopped during traveling of the vehicle using discharge electric power of the secondary battery. According to Japanese Patent Application Publication No. 2008-312282 (JP 2008-312282 A), the over-discharge resulting from further discharge in a non-over-discharge state is detected in advance and a discharge current of a battery module is decreased when the detection is performed in view of this point. In other words, discharging of the battery module is limited before the battery module is put into the over-discharge state so that the sudden stop of the vehicle is suppressed.
In JP 2008-312282 A, only discharge control until the battery module reaching the over-discharge state for suppressing the sudden stop of the vehicle is disclosed. Accordingly, charging and the discharging of the battery module are stopped as described above if the battery module is put into the over-discharge state. As a result, the vehicle is stopped.